穿山甲做為挖洞者所扮演之生態角色

Abstract

穿山甲是全球性瀕危物種；在臺灣，中華穿山甲（Manis pentadactyla）雖曾經歷棲息地喪失和盜獵威脅導致族群數量下降，但近年來其族群有漸趨穩定的趨勢。中華穿山甲擁有挖掘深長洞穴的能力。牠們不斷挖掘許多洞穴，但每個洞穴僅在短時間內使用，因此留下許多未被占據的空洞穴；這些洞穴可能成為為其他動物所利用。在這項研究中，我們在北臺灣設置24台自動相機，來檢視其他哺乳動物如何利用這些洞穴。同時，我們測量了洞穴入口寬度、洞穴入口與地面間角度、洞穴附近其他洞穴密度，以檢測這些洞穴特徵值是否能促進當地哺乳動物的多樣性和活動量。結果顯示，有來自12種哺乳動物共4,321 筆對穿山甲洞穴利用行為的記錄，提供包括檢視洞穴（75%）、入內棲息（20%）、洞外覓食（3%）、入內築巢（1%）等。主要的洞穴使用者是鼬獾（Melogale moschata；69%），牠們對這些洞穴的利用行為十分多樣化且經常深入洞穴。此外，鼬獾與麝香貓 (Viverricula indica)會使用洞穴繁殖。亦即，穿山甲為初級洞巢者，而鼬獾與麝香貓為次級洞巢者。最後，我們發現哺乳動物的總活動量、穿山甲活動量、麝香貓活動量皆與洞穴密度之間存在正向關係。根據這些結果，我認為穿山甲洞穴可做為共域哺乳動物的資源，並具有調節該地生態系中物種互動的潛力。Pangolin is a globally endangered species; in Taiwan the Chinese pangolin (Manis pentadactyla) is showing signs of recovery after a period of population decline due to habitat lose and poaching. The Chinese pangolin has the ability to excavate deep, long burrows. They routinely excavate new burrows because they typically use a burrow only for a short period of time. This behavior leads to many vacant burrows that could be used by other animals. In this study we examined how other mammals utilized these burrows by monitoring 24 burrows in northern Taiwan with field cameras. In order to assess whether burrow characteristics (i.e. width of burrow entrance, angle between burrow entrance and the ground, density of nearby burrows) influence mammal species richness and activity level at the local scale, we measured these burrow characteristics concurrently with the camera monitoring. Our results of 4,321 video records indicated that there were 12 mammal species utilizing the pangolin burrows. Their burrow-using behaviors included burrow investigating (75%), sheltering inside burrow (20%), foraging around burrow entrance (3%), and nesting/denning inside burrow (1%). The main secondary burrow user was the Chinese ferret badger (Melogale moschata; 69%), exhibiting a broad range of burrow-using behaviors and venturing deep into the burrows. On the other hand, the ferret badgers and small Indian civets (Viverricula indica) were found using the burrows as nesting/denning sites. That is, the pangolins were the primary burrow nesters whereas the ferret badgers and small Indian civets were the secondary burrow nesters. Finally, there wasa positive relationship between the burrow density and the activity level of all mammals, the pangolins or the small Indian civets. Based on these findings, I demonstrated that pangolin burrows can serve as a resource for other mammal species, and could potentially mediate species interaction in local ecosystems.